Textile fiber drafting apron



1961 E. LI'HOWELL 3,011,221

' TEXTILE FIBER DRAFTINGAPRON File'd May 15, 1957 EMORY 1.. HOWELL I INVENTOR.

g m Mae/V ATTORNEY United States Patent 3,011,221 TEXTILE FIBER DRAFTING APRON Emory L. Howell, Greenville, S.C., assignor to Dayco Corporation, a corporation of Ohio Filed May 15, 1957, Ser. No. 655L283 2 Claims. (Cl. 19-131) The present invention relates to elements for textile processing machinery and particularly to roll covers and drafting aprons for use in the formation of thread or yarn from textile fibers or the like.

In the manufacture of thread or yarn, individual, staple-length fibers of textile or synthetic material are first sorted by an operation known as carding into fibrous strips, known as slivers wherein the individual fibers are loosely associated and generally longitudinally aligned. Such strips are thereafter condensed, drawn or drafted, and spun to form a thread or yarn wherein the individual fibers are tightly compacted and twisted so as to impart considerable tensile strength to the strand. The drawing or drafting of the fibers is generally achieved by passing the same through a series of pairs of nearly tangentially contacting rollers and/or aprons, the peripheral speeds of which increase successively throughout the series so that those pairs which are forward or in the direction of thetravel of the sliver will tend to pull and draw out the strand while the rollers and aprons rearwardly thereof will act as a brake thereon.

In most of the drafting systems currently in use such as the Whitin-Casablancas and the Saco Lowell-Roth systems, at least one apron in the form of a flexible sleeve having an outer fiber contacting surface is employed. Such aprons are motivated by a powered roller in driving contact with the inner surface of the sleeve at the rear thereof. To provide a planar apron surface for contacting the fiber, a supporting rod often referred to as a nose bar is employed to hold the apron at the front thereof so that the normally cylindrical sleeve is held in elongated position during its travel about the driving roller and the nose bar. The nose bar itself vis stationary and is so contoured and polished that the apron will slide readily thereover.

Aprons supported and driven as above described, are employed in combination with a second apron or a roller which cooperates with the first apron to provide a means for simultaneously gripping the fibrous strand both on its top and bottom. This gripping is achieved .by causing the aprons and/or the apron and roller to be closely spaced along a portion of their respective surfaces at which point the opposed surfaces move in the same di-.

Because of this roller surfaces which are gripping thefibrous strand 3,011,221 Patented Dec. 5, 1961 it being found that improved drafting in fewer operations might be thereby achieved. As the spacing between the rollers or aprons at the point where the aprons are supported by the nose bar has been thus diminished, the nominal amplitude of the vibration of the apron sliding over the bar has become an even more significant factor in the loss of uniformity in the fibrous strand being drawn. To counteract this, the art has resorted to thinner drafting aprons, but this has proven undesirable in that such aprons have not provided a suflicient resilient body for proper drafting.

It is accordingly an object of the present invention to provide an improved element for textile working malchinery.

It is a more specific object of the present invention to provide an improved apron for use in fiber drafting machinery.

It is still a further object of the present invention to provide a drafting apron for use in drawing machinery wherein the apron slides over a stationary supporting rod or nose bar such as in the Whitin-Casablancas and the Saco Lowell-Roth systems.

It is still another object of the present invention to provide a fiber drafting apron which will not vibrate in passing over the nose bar and cause a cockling of the thread or yarn being processed thereby.

Still a further object of the present invention is to provide such a drafting apron which will form a thread or yarn of uniform cross section even where there is a very small spacing between the opposed fiber contacting surfaces of the aprons and/or drawing rollers.

It is still a further object of the present invention'to provide a method for'the manufacture of such a fiber drafting apron.

These and other objects and advantages of the present invention which will be apparent from a reading of the following disclosure'are achieved by incorporating a physically and chemically inert lubricant in the material forming the innermost surface of the sleeve-like apron body, such surface being that which comes in Sliding contact with the apron supporting rod or nose bar. This inertness of the lubricant to be employed must be complete however, and it is to be distinguished from substances which are normally referred to as being inert. For example, where, as is usually the case, the material forming the innermost surface of the apron sleeve is of an elastomeric nature such as rubber or one of the synthetic rubbers, the lubricant must be such that under no conditions will it enter into anyfcombination withthe elastomeric matrix, This is an important requirement in the case of the present invention particularly where the innermost apron surface is composed of a vulcanizable elastomeric material such as rubber or thesynthetic rubbers since, to achieve the purposes 'of this invention, the lubricant must be added vduringthe initial compounding and cannot be merely applied to the working surfaces after the apron has been completed. Thus the lubricant must withstand vulcanizing heat and pressure without undergoing any change or in any way combining with the rubber.

. fluorine-containing hydrocarbons including fluorocarbon practice to reduce suchspacing to from fl to 5 millimeters,

consistency similar, to that of petrolatum, 'Such a lubri:

polymers such as tetrafiuoroethylene and ch-lorotrifiuoro ethylene orcopolymers of chlorotrifluoroethylene and cant may be included with eflfectiveness in a rubber or synthetic rubber compound and particularly in a compound based upon a butadiene-acrylonitrile copolymer known as Buna-N in the range of from V to 10 parts by weight of the lubricant to 100 parts by weight of the rubber or synthetic rubber copolymer. Optimum results however, are achieved where the lubricant is incorporated in the range of from to 2 parts by weight based upon 100 parts by weight of the rubber-like material.

One preferred recipe for a compound which has been found capable of providing the improvements sought by the present invention is as follows:

Parts by weight Copolymer of butadiene-acrylonitrile [medium As previously explained, the fluorocarbon lubricant, because it is so completely inert, is miscible but not compatible in any way with the synthetic rubber and is therefore uniformly dispersed throughout the entire material and is present at the innermost apron surface formed thereby to permanently remove any residual tack that is otherwise inherent in such a compound. Because of this tack removal and the peculiar surface properties imparted by the presence of the fluorocarbon polymer in its unchanged state, the apron will pass smoothly about the nose bar Without any such vibrations or movement as will impair the uniformity of the fiber drafting or the thread or yarn resulting therefrom.

In the drawings:

FIGURE 1 is a schematic elevational view in partial cross section of a Whitin-Casablancas system fiber drafting unit in connection with which drafting aprons according to the present invention may be advantageously employed.

FIGURE 2 is an enlarged fragmentary perspective view in partial cross section showing an apron according to the present invention as it passes about a nose bar.

In FIGURE 1, the sliver or loosely compacted fibrous strand 10 moves in the direction of the arrows through the bite 11 of the substantially tangentially contacting drawing rollers 12"and 13. Then the strand passes through the closely spaced, parallel surfaces of the mated fiber drafting aprons 14 and 15 which are counter rotating so that the opposed surfaces are both moving in the direction of the sliver.' Thereafter the strand passes through thebite 16 of the front drawing rollers 17 and 18. The drawing rollers 12, 13, 17 and 18 orat least one of each pair of such rollers is preferably provided with a relatively soft or deformable surface such asone composed 'of synthetic rubber so that the rollers in each pair will grip the strand and make the sliver speed dependent upon the peripheral speed of the rolls. In this manner, the peripheral speed of the rear rollers 12 and 13 may be made to be less than that of the aprons 14 and 15 which in turn will be made to travel much more slowly than the front drawing rollers 17 and 18 so that between each successive pair of rollers and aprons, the sliver 10 will be more finely drawn and, closely compacted preparatory to its entering upon the spinning or twisting operation after leaving the front drawing rollers 17 and 18.

As previously stated, the aprons 14 and 15 are driven by at least one 'of the vertically opposed rolls 19 or 20. In most cases just one of these rollers, usually the lower roller 20 is powered, and its contact with the apron 15 and the contact of the apron 15 with the apron 14 will set the entire apron assembly including the upper apron 14 and the apron roller 19 in motion. The lower apron 15 will move in a counter-clockwise direction and the upper apron will move clockwise so that the opposed, parallel and closely spaced fiber-contacting areas 21 and 22 will move in the same direction along with the sliver 10. To hold the aprons in an extended position to maintain the parallel surfaces 21 and 22, the drafting machinery provides the supporting rods or nose bars 23 and 24, the forward surfaces of which are rounded and smooth to allow the apron to slide freely thereover, the bars themselves being stationary.

These nose bars 23 and 24 are so spaced that the op posed parallel apron surfaces 21 and 22 will at least gently contact the fibrous strand passing between them. Where aprons of a thickness on the order of .032 inch are employed, it has long been the practice to space the nose bars vertically by a distance of from 7 to 8 millimeters. More recently however, this spacing has been reduced to from 4 to 5 millimeters. While this closer spacing has resulted in improved and quicker drafting, it has enhanced the deleterious effect of the chattering or vibration of the aprons as they are forced by the rear drive over and around the bars.

As shown in FIGURE 2, one preferred embodiment of the present invention is a drafting apron composed of an outer layer 25 of an elastomeric material such as rubber or a synthetic rubber such as Buna-N which provides an outer, fiber contacting surface 26. The apron also comprises an inner layer 27 of an elastomeric material such as Buna-N with which from V to 10 parts by weight of an oily or waxy fluorocarbon polymer to parts by weight of the Buna-N are compounded. This inner layer presents the innermost surface 28 of the apron sleeve which is that contacted by the driving roller such as 20 in FIGURE 1 and makes'sliding contact with the nose bars such as 29. It is this surface which therefore has the critical friction requirements. If it is desired to reinforce the apron against longitudinal extension, an intermediate layer of helically wound inextensible cord such as cotton or rayon, may be employed. Where this two-layer construction is employed, the innermost layer may be composed according to the present invention to provide the improved friction qualities sought hereby, while the outermost layer may be compounded exclusively for improved fiber contact and drafting without any such lubricant therein as might result in damage to the fibers coming in contact with the same.

In the manufacture of aprons according to the present invention, the elastomeric material for the inner and outer layers is compounded according to usual practice as in an internal mixer or on a mill and is then calendered into sheets or layers of suflicientgauge to provide the desired apron thickness after grinding or other finishing. The

outer layer may be according to any well known rubberlike compound for use in drafting aprons such as that described in US. Patent No. 2,341,656 which issued February 15, 1944, to Joseph Rockoff while the inner layer is compounded as described above. Once again it is important in the compounding of the inner layer 27 that the fluorocarbon polymer be introduced at thecompounding and mixing stage so that it will beuniformlymixed and distributed throughout the entire stock.

The layers thus formed may be wrappedabout a'suitable building mandrel, the inner layer of course being first wrapped, then the longitudinal reinforcing cord if desired, and then the outer layer. The apron sleeve thus laminated is then compacted as for example by rag wrapping and subjected to conditions of heat and/ or pressure for vulcanization and finishing, all as described and illustrated in the above mentioned Rockoif patent.

The term rubber employed herein is meant to include natural rubber, the various synthetic rubbers such as the polymers and copolymers of butadiene, styrene, acrylonitrile, chloroprcne and polysulfide as well as other elastomers, vulcanizable or otherwise such as polyvinylchloride, polyethylene, polyurethane and similar organic plastic materials having rubber-like properties.

While the present invention has been described in considerable detail in connection with certain preferred embodiments thereof, it is to be understood that all of such particularization and detail have been for purposes of illustration only and do not limit the scope of the invention as it is defined in the subjoined claims.

I claim:

1. A textile fiber drafting apron having inner and outer layers of rubber, said inner layer having a fluorine-containing hydrocarbon lubricant dispersed therethrough, said lubricant being incompatible with said rubber and present in the range of to 10 parts per 100 parts by weight of mbber in said inner layer.

2. A textile fiber drafting apron according to claim 1 having two parts of lubricant to 100 parts by weight of rubber in said inner layer.

References Cited in the file of this patent UNITED STATES PATENTS 2,099,970 Casablancas Nov. 23, 1937 2,450,408 Baymiller Oct. 5, 1948 2,497,046 Kropa Feb. 7, 1950 2,681,324 Hochberg June 15, 1954 2,710,290. S afford et al. June 7, 1955 2,718,452 Lontz Sept. 20, 1955 2,719,833 Vincent et al. Oct. 4, 1955 2,804,886 White Sept. 3, 1957 2,811,752 Garret Nov. 5, 1957 OTHER REFERENCES "TefionTetrafiuoroethylene Fiber, article in Textile World Magazine, pages 82-83, September 1956. 

